very pretty - is the surface decoration formed by blowing it out causing the crackles rather than it being an acid etched decoration maybe? can't remember the details but some Walsh glass has this effect near the rim I think .m

very pretty - is the surface decoration formed by blowing it out causing the crackles rather than it being an acid etched decoration maybe? can't remember the details but some Walsh glass has this effect near the rim I think .m

I looked up Walsh and came across an iridescent blue bowl marked Walsh England, but the description says "typical wide ground pontil" whereas this is unmarked and has a small ground pontil mark.During a google search last week I came across Fenton stretch glass bowls where the iridescence is applied first and there are 'stretch marks' in the iridescence as the glass has expanded. Checked for that on the bowl and it's not one of those.The etched surface looks like acid has been sprayed on the top half of the outer surface and has run down the sides of the bowl, leaving smaller holes and lines on the upper half and longer lines on the lower half. It hasn't eaten into the iridescence so that must have been applied afterwards. The foot hasn't been etched or iridised so it must have been applied last.

Iridescence is the result of metal salts vapourised onto the surface, there is no acid involved. The process of cracking open a layer by blowing out, widely used by Leerdam and by Fenton in the late twenties, is actually based on tin. These processes are called tin crackle and stretch glass. This item is just iridescent thickwalled and might have been made by Robert Held in Vancouver - or by any other studio using iridescence.

yes sorry for any confusion NMott, I wasn't suggesting it was Walsh, just using Walsh as an example of where you might find this crackle in the iridescent caused as Ivo has described rather than by acid etching.m

Iridescence is the result of metal salts vapourised onto the surface, there is no acid involved. The process of cracking open a layer by blowing out, widely used by Leerdam and by Fenton in the late twenties, is actually based on tin. These processes are called tin crackle and stretch glass. This item is just iridescent thickwalled and might have been made by Robert Held in Vancouver - or by any other studio using iridescence.

Interesting.

Just to clarify, this item is acid etched and iridised, so two processes have been used for the surface decoration.

yes sorry for any confusion NMott, I wasn't suggesting it was Walsh, just using Walsh as an example of where you might find this crackle in the iridescent caused as Ivo has described rather than by acid etching.m

No worries, just thought I'd double check just in case it was one of them.